1. Field of the Invention
This application relates to a wireless communication apparatus, wireless communication system and transmitting power control method. They are available, for example, to apply to an ad-hoc network performing a multi-hop communication.
2. Description of the Related Art
As described in the publication, Network Working Group Request for Comments 3626, Optimized Link State Routing Protocol by Clausen et. al. (Project Hipercom, INRIA, October 2003), a wireless communication apparatus may produce neighbor tables describing the information of a neighboring wireless communication apparatus, and a routing table describing the route to a destination wireless communication apparatus, by a routine control packet transaction among wireless communication apparatuses by applying OLSR (the Optimized Link State Routing) as a proactive-type routing protocol that makes a route before a communication request.
The source wireless communication apparatus outputs a data packet arranged with information of an arbitrary destination wireless communication apparatus by reference to the neighbor table and the routing table made as mentioned above, and the data packet is sent to the destination wireless communication apparatus through a relay node.
When a density of arranged wireless communication apparatuses is high, and there are many wireless communication apparatuses neighboring other wireless communication apparatuses, interference from a radio wave may occur. Also, collisions of packets such as, for example, a control packet with a data packet, may often occur. Routes typically become unsteady, and packets are often lost. As one method for solving these problems, at least the range of access of radio waves is decreased by reducing the transmitting power in high density areas of the wireless communication apparatuses. In this case, there is also an advantage of possibility of reducing a dissipation power of the wireless communication apparatus by reducing a transmitting power of the wireless communication apparatus.
However, if the transmitting power from each wireless communication apparatus is reduced, the range of access of radio waves is reduced and there is a possibility that a connectivity of a wireless communication is not maintained.
Therefore, a need exists for a wireless communication apparatus, a wireless communication system and a transmitting power control method that will maintain connectivity in a wireless network, and prevent interference from radio waves and collision of packets.